When weighing a substance on an analytical balance with a closable weighing space, one of the movable housing parts has to be opened and subsequently closed again for charging of the balance. For a single measuring-out of a weighing commodity, for instance with a spatula, at least fifteen handling steps have to be accomplished in the case of known balances. That is, a housing part (window) must be opened, the receptacle has to be positioned on the balance dish, the housing part must be closed, the taring operation has to be accomplished, the spatula has to be picked up, the weighing commodity must be put on the spatula, the housing part has to be opened, the commodity has to be measured out, the spatula to be removed from the weighing space, the air current guard must be closed, the result has to be awaited, the air current guard must be opened, the receptacle has to be removed and the air current guard closed again.
The opening and closing of the air current guard, six times in total, requires always putting away either the receptacle or the spatula, both of which implements are already in the hands of the operator at the start of the weighing process and which he has to put down again after the termination of the weighing process. The handling steps are cumbersome and time-consuming, since the hand that also holds the spatula must regularly open the weighing space and close the same.
From the Swiss patent publication No. 559 901, a balance is known, in which the two side housing parts (sliding windows) are connected with each other through a coupling arrangement for synchronously opening and closing, whereby the operation is possible with the left as well as the right hand. It is achieved in this manner that one hand respectively remains free for an additional manipulation or for holding of an object, so that the sliding window can simultaneously be opened with the other hand.
This known device does not offer a solution for the thorough reduction of the handling steps.
The present invention is based on the task of doing away with the shortcomings in the operation of an analytical balance and to free the operator from the manual opening and closing of the movable housing parts.